The art of laser welding is relatively well known. In general, with reference to FIG. 1, first and second work pieces, embodied as an upper work piece 100 laid on a lower work piece 120 along a weld interface 180, become welded to one another by way of an irradiated beam 140 of laser light. As is known, the beam 140 passes through the upper work piece, which is laser light absorbent, where it gets absorbed by the lower work piece, which is opaque to laser light. As the beam irradiates, the weld interface heats up and causes the bottom surface of the upper work piece and the upper surface of the lower work piece to melt and meld together. Upon cooling, a weld joint remains. An optical path between a laser light source (not shown) and the to-be-welded work pieces may include a lens 160, for proper focusing, or other optical elements, such as mirrors, fiber optic strands, scanning structures or other. A clamping device (not shown) typically provides a pressing engagement of the work pieces to maintain relative positioning and good surface contact during welding. Those skilled in the art also know that the beam may weld as an advancing beam of light (embodied as either the beam of light moving relative to stationary work pieces, work pieces moving relative to a stationary beam or both moving relative to one another) during contour welding or as a simultaneous weld (embodied as an entirety of a weld interface being welded at the same time by a light beam with substantially no movement of the work pieces or beam).
As is apparent in FIG. 1, the two work pieces 100, 120 comprise generally uniformly shaped and flat structures with a relatively lengthy weld interface. Thus, under heat and pressure during welding, the weld joint along the weld interface 180 does not suffer any appreciable collapse.
With reference to FIGS. 2A and 2B, however, sometimes the work pieces do not embody uniformly shaped and flat structures as representatively shown with a to-be-welded lid 200 and container 220, nor do they always have a lengthy weld interface between the to-be-welded surfaces 210, 212. In such instances, when heat and pressure become applied during welding, the weld joint 240 adversely suffers from bowing effects or other. Moreover, sometimes the work pieces additionally contain a corner region 250 that prevents sufficient heating of the weld interface which further exacerbates the bowing condition. Often times bowing leads to undesirable manifestations, such as stress cracks.
Accordingly, a need exists in the laser welding arts for efficaciously laser welding two work pieces despite the work pieces embodying non-uniformly shaped or flat structures and/or having relatively small or short weld interfaces.
Regarding the technology of inkjet printing, it too is relatively well known. In general, an image is produced by emitting ink drops from an inkjet printhead at precise moments such that they impact a print medium, such as a sheet of paper, at a desired location. The printhead is supported by a movable print carriage within a device, such as an inkjet printer, and is caused to reciprocate relative to an advancing print medium and emit ink drops at such times pursuant to commands of a microprocessor or other controller. The timing of the ink drop emissions corresponds to a pattern of pixels of the image being printed. Other than printers, familiar devices incorporating inkjet technology include fax machines, all-in-ones, photo printers, and graphics plotters, to name a few.
A conventional thermal inkjet printhead includes access to a local or remote supply of color or mono ink, a heater chip, a nozzle or orifice plate attached to the heater chip, and an input/output connector, such as a tape automated bond (TAB) circuit, for electrically connecting the heater chip to the printer during use. The heater chip, in turn, typically includes a plurality of thin film resistors or heaters fabricated by deposition, masking and etching techniques on a substrate such as silicon.
To print or emit a single drop of ink, an individual heater is uniquely addressed with a small amount of current to rapidly heat a small volume of ink. This causes the ink to vaporize in a local ink chamber (between the heater and nozzle plate) and be ejected through and projected by the nozzle plate towards the print medium.
During manufacturing of the printheads, a printhead body gets stuffed with a back pressure device, such as a foam insert, and saturated with mono or color ink. A lid adheres or welds to the body via ultrasonic vibration. Ultrasonic welding, however, has often cracked the heater chip, introduced and entrained air bubbles in the ink and compromised overall printhead integrity. Adhering has an impractically long cure time.
Even further, as demands for higher resolution and increased printing speed continue, heater chips are often engineered with more complex and denser heater configurations which raises printhead costs. Thus, as printheads evolve, a need exists to control overall costs, despite increasing heater chip costs, and to reliably and consistently manufacture a printhead without causing cracking of the ever valuable heater chip.